Update README.md [skip ci]

README.md

@@ -2,47 +2,53 @@
 
 [Development Vlog](https://www.youtube.com/playlist?list=PLbpl-gZkNl2COf_bB6cfgTapD5WduAfPz) | [Contributing](https://github.com/isledecomp/isle/blob/master/CONTRIBUTING.md) | [Matrix](https://matrix.to/#/#isledecomp:matrix.org) | [Forums](https://forum.mattkc.com/viewforum.php?f=1) | [Patreon](https://www.patreon.com/mattkc)
   
-This is a **work-in-progress** decompilation of LEGO Island version 1.1. It aims to be relatively faithful, but not byte accurate. The goal is to provide a workable codebase that can be modified, improved, and ported to other platforms later on.
+This is a **work-in-progress** decompilation of LEGO Island version 1.1. It aims to be as accurate as possible, matching the recompiled instructions to the original machine code as much as possible. The goal is to provide a workable codebase that can be modified, improved, and ported to other platforms later on.
 
 ## Status
 
 <img src="https://github.com/isledecomp/isle/releases/download/continuous/ISLEPROGRESS.PNG" width="50%"><img src="https://github.com/isledecomp/isle/releases/download/continuous/LEGO1PROGRESS.PNG" width="50%">
 
-Currently `ISLE.EXE` is completely decompiled, however there are some known inaccuracies. It should work if you pair it with the original game's `LEGO1.DLL` (and other files), however small things may not work correctly yet. Work on decompiling `LEGO1.DLL` has only just started and currently it is too incomplete to be usable.
+Currently `ISLE.EXE` is completely decompiled and behaves identically to the original. A handful of stubborn instructions are not yet matching, however we anticipate they will as more of the overall codebase is implemented.
+
+`LEGO1.DLL` is still very much incomplete and cannot be used at this time. Instead, if you want to test this, it is recommended to pair the recompiled `ISLE.EXE` with the `LEGO1.DLL` from the original game.
 
 ## Building
 
-LEGO Island was compiled with Microsoft Visual C++ 4.20, so that's what this decompilation targets. However it should compile with NMAKE on newer versions of Visual Studio too.
+This projects uses the [CMake](https://cmake.org/) build system, which allows for a high degree of versatility regarding compilers and development environments. For the most accurate results, it is recommended to use Microsoft Visual C++ 4.20 (the same compiler used to build the original game). Since we're trying to match this to the original executable as closely as possible, all contributions will be graded with the output of this compiler.
 
-### Recommended Instructions
 
-These instructions use the development IDE from Visual C++ 4.20. By modern standards, it can be a little clunky to use, especially on newer versions of Windows, however it's still relatively straightforward. If you prefer a command line process that can fit into a modern workflow/IDE, see the instructions below.
+These instructions will outline how to compile this repository into an accurate instruction-matching binary with Visual C++ 4.2. If you wish, you can try using other compilers, but this is at your own risk and won't be covered in this guide.
 
-1. Install Microsoft Visual C++ 4.20. This can be found on many abandonware sites, but the installer can be a little iffy on modern versions of Windows. For convenience, I made a [portable version](https://github.com/itsmattkc/msvc420) that can be downloaded and used quickly instead.
+#### Prerequisites
-2. Download and install the DirectX 5 SDK. Similarly, this can be found on many abandonware sites.
-3. Open "Microsoft Developer Studio" (`BIN/MSDEV.EXE` for those using the portable).
-4. `File` > `Open Workspace`
-5. Select `ISLE.MDP` from this repository.
-6. Select a build configuration. `ISLE - Win32 Release` is recommended because, at this point in time, you'll almost certainly be pairing it with the retail `LEGO1.DLL`, which is also a release build.
-7. `Build` > `Build ISLE.EXE`. This will build `ISLE.EXE` in a folder called `Release`. It will also build `LEGO1.DLL` since it's listed as a dependency, however the `LEGO1.DLL` produced is too incomplete to be usable at this time.
 
-### Command Line Instructions
+You will need the following software installed:
 
-For some users, this may be preferable to using an obsolete graphical IDE. Any modern IDE should support custom command line build steps, making this potentially easier to fit into a familiar contemporary workflow. This guide assumes a general familiarity with the Windows command prompt.
+- Microsoft Visual C++ 4.2. This can be found on many abandonware sites, but the installer can be a little iffy on modern versions of Windows. For convenience, I made a [portable version](https://github.com/itsmattkc/msvc420) that can be downloaded and used quickly instead.
+- DirectX 5 SDK. Similarly, this can be found on many abandonware sites.
+- [CMake](https://cmake.org/). A copy is often included with the "Desktop development with C++" workload in newer versions of Visual Studio, however it can also be installed as a standalone app.
 
-1. Acquire Visual Studio/Visual C++. Any version after 4.20 should work here, but 4.20 is the only one guaranteed to work. If you wish to use 4.20, it can be found on many abandonware sites, but the installer can be a little iffy on modern versions of Windows. For convenience, I made a [portable version](https://github.com/itsmattkc/msvc420) that can be downloaded and used quickly instead.
+#### Compiling From Command Line
-2. Download and install the DirectX 5 SDK. Similarly, this can be found on many abandonware sites, but later versions of Visual Studio include the DirectX SDK by default, so this step may be skippable (you definitely need it for MSVC 4.20).
+
-3. Open an x86/32-bit developer command prompt. Depending on the version of VS you're using, you may have a start menu item for it already (e.g. `x86 Native Tools Command Prompt`). Alternatively, you can start a normal command prompt (`cmd`) and run `vcvars32.bat` from the Visual Studio folder (run `BIN/VCVARS32.BAT x86` if you're using the portable 4.20).
+1. Open a Command Prompt (`cmd`).
-4. `cd` to the folder you cloned this repository to.
+1. From Visual C++ 4.2, run `BIN/VCVARS32.BAT x86` to populate the path and other environment variables for compiling with MSVC.
-5. `mkdir Release` if the folder doesn't already exist. Some versions of NMAKE may make this folder by itself, but some don't.
+1. Make a folder for compiled objects to go, such as a `build` folder inside the source repository (the folder you cloned/downloaded to).
-6. Run `nmake /f isle.mak CFG="ISLE - Win32 Release"`. This will build `ISLE.EXE` in the `Release` folder you just made. It will also build `LEGO1.DLL` since it's listed as a dependency, however the `LEGO1.DLL` produced is too incomplete to be usable at this time.
+1. In your Command Prompt, `cd` to the build folder.
+1. Configure the project with CMake by running:
+```
+cmake <path-to-source> -G "NMake Makefiles" -DCMAKE_BUILD_TYPE=RelWithDebInfo
+```
+  - Replace `<path-to-source>` with the source repository. Can be `..` if your build folder is inside the source repository.
+  - `RelWithDebInfo` is recommended because it will produce debug symbols useful for further decompilation work. However, you can change this to `Release` if you don't need them. `Debug` builds are not recommended because they are unlikely to be compatible with the retail `LEGO1.DLL`, which is currently the only way to really use this decomp.
+  - `NMake Makefiles` is most recommended because it will be immediately compatible with Visual C++ 4.2. For faster builds, you can use `Ninja` (if you have it installed), however due to limitations in Visual C++ 4.2, you can only build `Release` builds this way (debug symbols cannot be generated with `Ninja`).
+1. Build the project by running `nmake` or `cmake --build <build-folder>`
+1. When this is done, there should a recompiled `ISLE.EXE` and `LEGO1.DLL` in the build folder.
+
+If you have a CMake-compatible IDE, it should be pretty straightforward to use this repository, as long as you can use `VCVARS32.BAT` and set the generator to `NMake Makefiles`.
 
 ## Usage
 
 Simply place the compiled `ISLE.EXE` into LEGO Island's install folder (usually `C:\Program Files\LEGO Island` or `C:\Program Files (x86)\LEGO Island`). Unless you're a developer, disregard the compiled `LEGO1.DLL` for now as it is too incomplete to be usable. Alternatively, LEGO Island can run from any directory as long as `ISLE.EXE` and `LEGO1.DLL` are in the same directory, and the registry keys point to the correct location for the asset files.
 
-Ideally, this decompilation should be paired with version 1.1. It may work on 1.0 too, however this is not guaranteed.
-
 ## Contributing
 
 If you're interested in helping/contributing to this project, check out the [CONTRIBUTING](https://github.com/isledecomp/isle/blob/master/CONTRIBUTING.md) page.